Direkte Synthese von Ketonen aus primären Alkoholen und 1-Alkenen

Directing groups have been widely used in recent years to achieve control over all aspects of reaction selectivity in a wide range of transformations involving transition-metal catalysis and organometallic reagents. In cases when the existing functional group within a substrate is unsuited to achieve efficient intramolecular delivery of a reagent or catalyst, the specific introduction of an appropriately designed removable reagent-directing group can be a solution to this problem. In this Review we give an overview of the state of the art in this area, including the stoichiometric and catalytic use of directing groups.

show abstract

“…[132,133] However, in many cases a stoichiometric amount of the 2-aminopicoline as a catalyst-directing group was required.…”

Section: Intermolecular Rhodium-catalyzed Hydroacylationmentioning

confidence: 99%

Removable Directing Groups in Organic Synthesis and Catalysis

2011

View full text Add to dashboard Cite

show abstract

Ein hochaktives Katalysatorsystem für intermolekulare Hydroacylierungen

Jun

Lee

et al. 2000

Angewandte Chemie

Self Cite

View full text Add to dashboard Cite

show abstract

The Catalytic Alkylation of Aromatic Imines by Wilkinson's Complex: The Domino Reaction of Hydroacylation andortho-Alkylation

et al. 2000

Self Cite

View full text Add to dashboard Cite

Transition metal catalyzed C À H bond activation and the subsequent coupling of the organic fragment to an olefin is a promising area in which to find a convenient method for the construction of a carbon skeleton. [1] We have studied CÀH bond activation through the hydroacylation of olefins using aldehydes, alcohols, and aldimines. [2, 3] Unexpectedly during our experiments on transimination-assisted hydroacylation with aldimines, [3] ortho-alkylation was observed. Alkylation of aromatic ketones at the ortho position in a ruthenium(ii)catalyzed reaction has been reported by Murai and coworkers, this is an outstanding example of sp 2 -CH/olefin coupling and a decisive breakthrough in efficiency and selectivity. [4] However, while the reaction shows a high efficiency for vinyl silane or vinyl siloxane, it exhibits limitations for other olefins, for example low reactivity for 1-alkenes bearing allylic protons, probably because of facile double bond isomerization, and no reactivity for internal olefins and a,w-dienes. [5] Herein, we report an efficient orthoalkylation of aromatic imines with various olefins by using Wilkinsons complex ([Rh(PPh 3 ) 3 Cl] (3)) and hydroacylation. This ortho-alkylation is chelation-assisted and shows generality as well as regioselectivity, and high efficiency.Treatment of the aldimine 1 a [Eq.(1)] with tert-butylethylene (2 a) at 170 8C for 6 h with 3 (2 mol % based upon 1 a) H N CH 2 Ph tC 4 H 9 O tC 4 H 9 tC 4 H 9 O tC 4 H 9 a) [Rh(PPh 3 ) 3 Cl] (3), 2 mol%; 2-amino-3-picoline (4), 10 mol% 170 °C, 6 h b) H + /H 2 O 5a 6a + 5 % 90 % (1) + 1a 2aand 2-amino-3-picoline (4; 10 mol % based upon 1 a) as a cocatalytic system gave, after hydrolysis, compound 5 a in 90 % yield along with a small amount of 6 a (5 %). Compound 6 a is a hydroacylated product of 1 a and is formed by a transimination reaction, while 5 a is both a hydroacylated and an ortho-alkylated product. Of the various aldimines employed 1 a, prepared from benzylamine and benzaldehyde, showed the best reactivity for this simultaneous hydroacylation and ortho-alkylation. [3] Compound 1 a did not react with 2 a without the cocatalyst 4 [Eq.(2)], [2] whereas, the ketimine 1 b (which is the benzylimine of acetophenone) was ortho-alkylated by 2 a in the 1a 3 without 4 + 2a no reaction (2) presence of 3 alone, to give 7 a in 97 % yield [Eq. (3)]. These results show that the rhodium(i)-catalyzed ortho-alkylation takes place in ketimines, not in aldimines and that there is no ortho-alkylation without hydroacylation. CH 3 N CH 2 Ph CH 3 O tC 4 H 9 a) 2 mol% 3, toluene 150 o C, 2 h + b) H + /H 2 O 2a 97 % 1b 7a(3)Ketimine 1 b was very reactive in the ortho-alkylation reaction with 3; thus, various olefins were tested in reactions with this ketimine 1 b and 3 as catalyst (Table 1). In contrast to When the emission spectra of the CPFs in methanol (10 % sodium phosphate buffer) excited at 370 nm were detected, the emission of the fluorescein acceptor could be observed in all CPFs. The hydrophobic interaction between the fluorophores wo...

show abstract

Direkte Synthese von Ketonen aus primären Alkoholen und 1-Alkenen

Cited by 26 publications

References 27 publications

Removable Directing Groups in Organic Synthesis and Catalysis

Removable Directing Groups in Organic Synthesis and Catalysis

Ein hochaktives Katalysatorsystem für intermolekulare Hydroacylierungen

The Catalytic Alkylation of Aromatic Imines by Wilkinson's Complex: The Domino Reaction of Hydroacylation andortho-Alkylation

Contact Info

Product

Resources

About